An active matrix organic light emitting diode (AMOLED) display is more suitable to performance requirements of displays in an age of multimedia due to its advantages of non-angle limitation, low manufacturing cost, high response speed (approximately more than hundred times of a liquid crystal display), power saving, self-luminescent, direct current driving applicable to portable devices, wide range of operating temperature, light weight and becoming smaller and thinner according to the hardware devices and so on. Therefore, the AMOLED display has great potential for development, and is expected to take place of the liquid crystal display to become a younger generation of a new-type flat panel display.
Each pixel of the AMOLED display is constituted of three sub-pixels, i.e., red, green and blue, or four sub-pixels, i.e., red, green, blue and white. Each sub-pixel has its respective driving circuit correspondingly. People's requirement for display effect becomes higher and higher, resolution is increasingly rising, and device configuration of each pixel is closer and closer. As a result, the driving circuit would be damaged easily in massive industrial production due to situations such as instability of manufacturing environment and process, high current, etc., thereby causing a certain sub-pixel fails to operate normally. Then, a corresponding pixel would be lack of a color unit, such that bright points or dark points occur in the case of displaying. All of these belong to display defects, would reduce display quality, and have a great influence on the display effect.